Two-Phase Coupled Inductors Which Promote Improved Printed Circuit Board Layout

ABSTRACT

Two-phase coupled inductors including a magnetic core, at least a first winding, and at least three solder tabs. Power supplies including a printed circuit board, a two-phase coupled inductor affixed to the printed circuit board, and first and second switching circuits affixed to the printed circuit board. Each of the first and second switching circuits are electrically coupled to a respective solder tab of the two-phase coupled inductor affixed to the printed circuit board.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. patent applicationSer. No. 12/643,957 filed Dec. 21, 2009, which is incorporated herein byreference.

BACKGROUND

Switching DC-to-DC converters having a multi-phase coupled inductortopology are described in U.S. Pat. No. 6,362,986 to Schultz et al., thedisclosure of which is incorporated herein by reference. Theseconverters have advantages, including reduced ripple current in theinductors and the switches, which enables reduced per-phase inductanceand/or reduced switching frequency over converters having conventionalmulti-phase DC-to-DC converter topologies. As a result, DC-to-DCconverters with magnetically coupled inductors achieve a superiortransient response without an efficiency penalty compared withconventional multiphase topologies. This allows a significant reductionin output capacitance resulting in smaller, lower cost solutions.

As known in the art, coupled inductor windings must be inverselymagnetically coupled to benefit from a coupled inductor in a multi-phaseDC-to-DC converter design. Inverse magnetic coupling in a two-phaseDC-to-DC converter can be appreciated with reference to FIG. 1, whichshows a schematic of a two-phase DC-to-DC converter 100. DC-to-DCconverter 100 includes a coupled inductor 102, which includes twowindings 104, 106, and a magnetic core 108 magnetically couplingwindings 104, 106. A respective first terminal 110, 112 of each winding104, 106 electrically couples to a common node 114, and a respectivesecond terminal 116, 118 of each winding 104, 106 electrically couplesto a respective switching node 120, 122. In the present disclosure,terminals of a coupled inductor that are electrically coupled to arespective switching node in a DC-to-DC converter application (e.g.,terminals 116, 118 in DC-to-DC converter 100 of FIG. 1) will sometimesbe referred to as switching terminals of the coupled inductor.Additionally, terminals of a coupled inductor that are electricallycoupled to a common node (e.g., terminals 110, 112 in DC-to-DC converter100 of FIG. 1) will sometimes be referred to as common terminals of thecoupled inductor in the present disclosure.

A respective switching circuit 124, 126 is also electrically coupled toeach switching node 120, 122. Each switching circuit 124, 126 switchesits respective second terminal 116, 118 between at least two differentvoltage levels. DC-to-DC converter 100 could be configured, for example,as a buck converter, where switching circuits 124, 126 switch theirrespective second terminal 116, 118 between an input voltage and ground,and common node 114 is an output node. As another example, DC-to-DCconverter 100 could be configured as a boost converter, where eachswitching circuit 124, 126 switches its respective second terminal 116,118 between an output node and ground, and common node 114 is an inputnode.

Coupled inductor 102 is configured such at it has inverse magneticcoupling between windings 104, 106. As a result of such inverse magneticcoupling, a current flowing through winding 104 from switching node 120to common node 114 induces a current in winding 106 flowing fromswitching node 122 to common node 114. Similarly, a current flowingthrough winding 106 from switching node 122 to common node 114 induces acurrent in winding 104 flowing from switching node 120 to common node114 because of the inverse coupling.

Various coupled inductors have been developed for use in multi-phaseDC-to-DC converter applications. For example, FIG. 2 shows a side viewof a prior-art two-phase (i.e., two winding) coupled inductor 200.Coupled inductor 200 includes two windings 202 wound through a magneticcore 204. FIG. 3 shows a perspective view of one winding 202 separatedfrom core 204. Although coupled inductor 200's design promotes ease ofprinted circuit board (PCB) layout and is scalable to more thantwo-phases, windings 202 are relatively complex, and inductor 200 maytherefore be difficult and costly to manufacture. Additionally, windings202 are relatively long and thus typically have relatively highimpedance.

As another example, two-phase coupled inductors with staple stylewindings have been developed. FIG. 4 shows a perspective view of a priorart two-phase coupled inductor 400, which is representative of suchinductors. Coupled inductor 400 includes two staple style windings 402wound through a magnetic core 404. In contrast to windings 202 ofcoupled inductor 200, staple style windings 402 are relatively simple,thereby promoting ease of manufacturing and low cost of coupled inductor400. Additionally, windings 402 have a relatively short length, therebypromoting low DC winding resistance. Therefore, coupled inductor 400generally has a lower cost and exhibits a lower winding resistance thanmany other types of prior coupled inductors, such as coupled inductor200 of FIG. 2.

However, a DC-to-DC converter including coupled inductor 400 must beconfigured such that one terminal on each side of the inductor iselectrically coupled to a respective switching node, to achieve inversemagnetic coupling. Specifically, a DC-to-DC converter including coupledinductor 400 is configured such that one terminal on side 406 iselectrically coupled to a respective switching node, and one terminal onside 408 is electrically coupled to a respective switching node, toachieve inverse magnetic coupling. Two terminals on a same side ofcoupled inductor 400 cannot serve as switching terminals if inversemagnetic coupling is to be realized. Such constraint imposed by coupledinductor 400 is undesirable in many DC-to-DC converter applications, asdiscussed below.

For example, a DC-to-DC converter including coupled inductor 400typically must be configured such that the converter's switchingcircuits are located on different sides of inductor 400. In particular,as known in the art, DC-to-DC converter switching circuits must belocated near their respective inductor switching terminals for reliableand efficient DC-to-DC converter operation. For example, in DC-to-DCconverter 100 of FIG. 1, switching circuit 124 needs to be located nearswitching terminal 116, and switching circuit 126 needs to be locatednear switching terminal 118, for efficient and reliable DC-to-DCconverter operation. Thus, in a DC-to-DC converter including coupledinductor 400, inductor switching terminals are on opposite sides ofcoupled inductor 400 to achieve inverse magnetic coupling, and theDC-to-DC converter switching circuits therefore generally must belocated on different (e.g., opposite) sides of coupled inductor 400 tobe near their respective inductor switching terminals. It can beundesirable to locate switching circuits on different sides of a coupledinductor as doing so may prohibit use of a common heat sink to cool allswitching circuits and/or complicate DC-to-DC converter layout whendriving a load accessed from one side of the converter.

As another example, a DC-to-DC converter including coupled inductor 400may require one or more PCB traces of long, narrow, and/or complex shapeto electrically couple terminals of the inductor to other components ofthe DC-to-DC converter. In particular, if a DC-to-DC converter includingcoupled inductor 400 is configured such that the inductor switchingterminals are on opposite sides of the coupled inductor to achieveinverse magnetic coupling, the DC-to-DC converter necessarily must alsobe configured such that the inductor common terminals are on oppositesides of the coupled inductor. The fact that the inductor commonterminals are on opposite sides of the inductor typically necessitates arelatively long, narrow, and/or complex shaped PCB trace to connect thecommon terminals to a common node. Narrow or long traces are generallyundesirable as they typically have high impedance, which may result inexcessive losses and/or unreliable operation. Complex shaped traces(e.g., non-rectangular) may also be undesirable as they may be difficultto manufacture and/or prone to short to other traces.

For example, FIG. 5 shows one prior art PCB layout 500 for use withcoupled inductor 400 in a two-phase DC-to-DC converter application. Onlythe outline of coupled inductor 400 is shown in FIG. 5 to show detailsfor layout 500. Layout 500 includes pads 502, 504, 506, 508 forelectrically coupling to terminals of coupled inductor 400. Pads 502,508, which electrically couple to respective switching nodes, arelocated on opposite sides 510, 512 of coupled inductor 400 to achieveinverse magnetic coupling. Switching circuits 514, 516 are respectivelycoupled to pads 502, 508 by conductive PCB traces 518, 520. Switchingcircuits 514, 516 are also located on opposite sides 510, 512 of coupledinductor 400. Pads 504, 506, which electrically couple to a common node,are also on opposite sides 510, 512 of coupled inductor 400. As a resultof pads 504, 506 being on opposite sides of inductor 400 and thelocation of switching circuits 514, 516, a relatively long and narrowconductive trace 522 is required to connect pads 504, 506 to a commonnode.

As another example, FIG. 6 shows another prior art PCB layout 600 foruse with coupled inductor 400 in a two-phase DC-to-DC converterapplication. Layout 600 includes pads 602, 604, 606, 608 forelectrically coupling to terminals of coupled inductor 400. Pads 602,608, which electrically couple to a respective switching circuit 610,612 via a respective conductive trace 614, 616, are located on oppositesides of coupled inductor 400 to achieve inverse magnetic coupling. Pads604, 606, which, electrically coupled to a common node via a conductivePCB trace 618, are also located on opposite sides of coupled inductor400. The fact that pads 604, 606 are on opposite sides of coupledinductor 400 and the location of switching circuits 610, 612 requiresconductive trace 618 to be relatively long and narrow and to have acomplex shape.

SUMMARY

In an embodiment, a two-phase coupled inductor includes a magnetic core,a first winding, and a second winding. The magnetic core includes afirst side and a second side opposite the first side, and the magneticcore forms a passageway extending through the core from the first sideto the second side. The passageway is partially defined by a first legof the magnetic core. The first winding is wound at least partiallyaround the first leg and through the passageway. A first end of thefirst winding extends from the first side of the core and forms a firstsolder tab, and a second end of the first winding extends from thesecond side of the core and forms a second solder tab. The secondwinding is wound at least partially around the first leg and through thepassageway. A first end of the second winding extends from the secondside of the core and forms a third solder tab, and a second end of thesecond winding extends from the first side of the core and forms afourth solder tab. The first, second, third, and fourth solder tabs areseparated from each other along a width of the magnetic core. Anelectric current flowing through the first winding from the first soldertab to the second solder tab induces an electric current flowing throughthe second winding from the third solder tab to the fourth solder tab.The two-phase coupled inductor may be used, for example, in a multiphasepower supply.

In an embodiment, a two-phase coupled inductor includes a magnetic coreincluding a first side and a second side opposite the first side. Themagnetic core forms a passageway extending through the core from thefirst side to the second side, and the passageway is partially definedby a first leg of the magnetic core. The coupled inductor furtherincludes a first winding forming at least two turns around the first legand wound through the passageway. A first end of the first windingextends from the first side of the core and forms a first solder tabalong a bottom surface of the coupled inductor, and a second end of thefirst winding extends from the second side of the core and forms asecond solder tab along the bottom surface of the coupled inductor. Anintermediate portion of the first winding between the first and secondends of the first winding forms a third solder tab along the bottomsurface of the coupled inductor. The first, second, and third soldertabs are separated from each other along a width of the magnetic core.An electric current flowing through the first winding from the firstsolder tab to the third solder tab induces an electric current flowingthrough the first winding from the second solder tab to the third soldertab. The two-phase coupled inductor may be used, for example, in amultiphase power supply.

In an embodiment, a two-phase coupled inductor includes a magnetic core,a first winding, and a second winding. The magnetic core includes afirst side opposite a second side, and the magnetic core forms apassageway extending through the core from the first side to the secondside. The passageway is partially defined by a first leg of the magneticcore. A first winding is wound at least partially around the first legand through the passageway. A first end of the first winding extendsfrom the first side of the core and forms a first solder tab, and asecond end of the first winding extends from the second side of the coreand forms a second solder tab. A second winding is wound at leastpartially around the first leg and through the passageway. A first endof the second winding extends from the first side of the core and formsa third solder tab, and a second end of the second winding extends fromthe second side of the core and forms a fourth solder tab. The firstwinding crosses the second winding within the passageway. The two-phasecoupled inductor may be used, for example, in a multiphase power supply.

In an embodiment, a two-phase coupled inductor includes a magnetic core,a first winding, and a second winding. The magnetic core includes afirst side opposite a second side, a third side opposite a fourth side,and a fifth side opposite a sixth side. The fifth side connects thefirst side to the third side. The fifth side forms an obtuse angle withthe first side and an obtuse angle with the third side. The sixth sideconnects the second side to the fourth side. The sixth side forms anobtuse angle with the second side and an obtuse angle with the fourthside. The magnetic core forms a passageway extending through the corefrom the fifth side to the sixth side, and the passageway is partiallydefined by a first leg of the magnetic core. The first winding is woundat least partially around the first leg and through the passageway. Afirst end of the first winding extends from the fifth side of the coreand forms a first solder tab, and a second end of the first windingextends from the sixth side of the core and forms a second solder tab.The second winding is wound at least partially around the first leg andthrough the passageway. A first end of the second winding extends fromthe fifth side of the core and forms a third solder tab, and a secondend of the second winding extends from the sixth side of the core andforms a fourth solder tab. The two-phase coupled inductor may be used,for example, in a multiphase power supply.

In an embodiment, a two-phase coupled inductor includes a magnetic core,a first winding, and a second winding. The magnetic core includes afirst side opposite a second side, and the magnetic core forms apassageway extending through the core from the first side to the secondside. The passageway is partially defined by first and second opposingsurfaces, and the magnetic core includes a first leg connecting thefirst and second surfaces within the passageway. The first winding iswound at least partially around the first leg. A first end of the firstwinding extends from the first side of the core and forms a first soldertab, and a second end of the first winding extends from the first sideof the core and forms a second solder tab. A second winding is wound atleast partially around the first leg. A first end of the second windingextends from the second side of the core and forms a third solder tab,and a second end of the second winding extends from the second side ofthe core and forms a fourth solder tab. The two-phase coupled inductormay be used, for example, in a multiphase power supply.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a schematic of a prior-art DC-to-DC converter.

FIG. 2 shows a side view of a prior-art coupled inductor.

FIG. 3 shows a perspective view of a winding of the FIG. 2 coupledinductor.

FIG. 4 shows a perspective view of another prior-art coupled inductor.

FIG. 5 shows a prior art PCB layout for use with the coupled inductor ofFIG. 4 in a two-phase DC-to-DC converter application.

FIG. 6 shows another prior art PCB layout for use with the coupledinductor of FIG. 4 in a two-phase DC-to-DC converter application.

FIG. 7 shows a perspective view,

FIG. 8 shows a top cross sectional view, and

FIG. 9 shows a side view of one two-phase coupled inductor, according toan embodiment.

FIG. 10 shows a perspective view of the windings of the coupled inductorof FIGS. 7-9 removed from a magnetic core of the coupled inductor.

FIG. 11 shows one PCB layout that may be used with certain embodimentsof the coupled inductor of FIGS. 7-9.

FIG. 12 shows a perspective view and

FIG. 13 shows a top cross sectional view of another two-phase coupledinductor, according to an embodiment.

FIG. 14 shows a perspective view of the windings of the coupled inductorof FIGS. 12 and 13 removed from a magnetic core of the coupled inductor.

FIG. 15 shows a perspective view,

FIG. 16 shows a top cross sectional view, and

FIG. 17 shows a side view of another two-phase coupled inductor,according to an embodiment.

FIG. 18 shows a perspective view of the windings of the coupled inductorof FIGS. 15-17 removed from a magnetic core of the coupled inductor.

FIG. 19 shows one PCB layout that may be used with certain embodimentsof the coupled inductor of FIGS. 15-17.

FIG. 20 shows a perspective view and

FIG. 21 shows a top cross sectional view of yet another two-phasecoupled inductor, according to an embodiment.

FIG. 22 shows a perspective view of the windings of the coupled inductorof FIGS. 20 and 21 removed from a magnetic core of the coupled inductor.

FIG. 23 shows a perspective view of another two-phase coupled inductor,according to an embodiment.

FIG. 24 shows a perspective view of the windings of the coupled inductorof FIG. 23 removed from the magnetic core of the coupled inductor.

FIG. 25 shows a perspective view,

FIG. 26 shows a top cross sectional view, and

FIG. 27 shows a side view of another two-phase coupled inductor,according to an embodiment.

FIG. 28 shows a perspective view of the winding of the coupled inductorof FIGS. 25-27 removed from a magnetic core of the coupled inductor.

FIG. 29 shows one PCB layout that may be used with certain embodimentsof the coupled inductor of FIGS. 25-27.

FIG. 30 shows a perspective view and

FIG. 31 shows a top cross sectional view of another two-phase coupledinductor, according to an embodiment.

FIG. 32 shows a perspective view of the windings of the coupled inductorof FIGS. 30 and 31 removed from the magnetic core of the coupledinductor.

FIG. 33 shows one PCB layout that may be used with certain embodimentsof the coupled inductor of FIGS. 30 and 31.

FIG. 34 shows a perspective view of another two-phase coupled inductor,according to an embodiment.

FIG. 35 shows a perspective view of the winding of the coupled inductorof FIG. 34 removed from a magnetic core of the coupled inductor.

FIG. 36 shows a perspective view,

FIG. 37 shows a top cross sectional view, and

38 shows a side view of another two-phase coupled inductor, according toan embodiment.

FIG. 39 shows a perspective view of the windings of the coupled inductorof FIGS. 36-38 removed from the magnetic core of the coupled inductor.

FIG. 40 shows one PCB layout that may be used with certain embodimentsof the coupled inductor of FIGS. 36-38, according to an embodiment.

FIG. 41 shows a perspective view and

FIG. 42 shows a top cross sectional view of another two-phase coupledinductor, according to an embodiment.

FIGS. 43 and 44 show perspective views of the windings of the coupledinductor of FIGS. 41 and 42 removed from the magnetic core of thecoupled inductor.

FIG. 45 shows a perspective view and

FIG. 46 shows a top view of another two-phase coupled inductor,according to an embodiment.

FIG. 47 shows a perspective view of the magnetic core of the coupled ofFIGS. 45-46 without the windings of the coupled inductor.

FIG. 48 shows a perspective view of the windings of the coupled inductorof FIGS. 45-46 removed from the magnetic core of the coupled inductor.

FIG. 49 shows a top cross sectional view of the coupled inductor ofFIGS. 45-46 installed on one PCB layout, according to an embodiment.

FIG. 50 shows a perspective view and

FIG. 51 shows a side view of another two-phase coupled inductor,according to an embodiment.

FIG. 52 shows a perspective view of the magnetic core of the coupledinductor of FIGS. 50-51 without the windings of the coupled inductor,and

FIGS. 53 and 54 show perspective views of the windings of the coupledinductor of FIGS. 50-51 removed from the magnetic core of the coupledinductor.

FIG. 55 shows a top cross sectional view of a two-phase coupled inductorinstalled on one PCB layout, according to an embodiment.

FIG. 56 shows a perspective view,

FIG. 57 shows a side view, and

FIG. 58 shows a top cross sectional view of another two-phase coupledinductor, according to an embodiment.

FIG. 59 shows a perspective view of the magnetic core of the coupledinductor of FIGS. 56-58 without the windings of the coupled inductor.

FIGS. 60 and 61 show perspective views of the windings of the coupledinductor of FIGS. 56-58 removed from the magnetic core of the coupledinductor.

FIG. 62 shows a perspective view of another two-phase coupled inductor,according to an embodiment.

FIG. 63 shows a top cross sectional view of a two-phase coupled inductorinstalled on one PCB layout, according to an embodiment.

FIG. 64 shows a schematic of a power supply, according to an embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Disclosed herein, among other things, are coupled inductors that mayovercome one or more of the problems discussed above. For example,certain embodiments of the coupled inductors disclosed herein not onlyhave relatively short winding lengths, but also may be used inmulti-phase DC-to-DC converters configured such that each power stage isdisposed on a common side of the coupled inductor. As another example,certain embodiments of the coupled inductors disclosed herein may beused in DC-to-DC converters where a relatively wide, short, and/orsimple shaped PCB conductive trace connects the coupled inductors'common terminals to a common node.

Although the coupled inductors disclosed herein are generally discussedin the context of DC-to-DC converters, it should be appreciated that thecoupled inductors are not limited to such applications. For example,certain embodiments of the coupled inductors disclosed herein could beused in AC-to-DC power supplies, in DC-to-AC power supplies (inverters),or in applications other than in switching power supplies. Furthermore,although a number of examples of PCB layouts are provided, the inductorsdisclosed herein could be used in other layouts. Moreover, for purposesof illustrative clarity, certain elements in the drawings may not bedrawn to scale. Specific instances of an item may be referred to by useof a numeral in parentheses (e.g., winding 6408(1)) while numeralswithout parentheses refer to any such item (e.g., windings 6408).

FIG. 7 shows a perspective view of one two-phase coupled inductor 700.Coupled inductor 700 includes a magnetic core 702, shown as transparentin FIG. 7. Magnetic core 702 includes a leg 704 and forms a passageway706 from a first side 708 to a second side 710 of core 702. Leg 704partially defines passageway 706. FIG. 8 shows a top cross-sectionalview of inductor 700 taken along line A-A of FIG. 7, and FIG. 9 showsside 708 of coupled inductor 700.

Coupled inductor 700 further includes staple style windings 712, 714,which promote ease of manufacturing and low cost of coupled inductor700, as well as low winding impedance. Windings 712, 714 are, forexample, foil windings to minimize the skin effect and thereby promotelow AC resistance. Each winding 712, 714 is wound at least partiallyaround leg 704 and through passageway 706 of core 702. A first end ofwinding 712 extends from first side 708 of core 702 and forms a firstsolder tab 716, and a second end of winding 712 extends from second side710 of core 702 and forms a second solder tab 718. A first end ofwinding 714 extends from second side 710 of core 702 and forms a thirdsolder tab 720, and a second end of winding 714 extends from first side708 of core 702 and forms a fourth solder tab 722. Each of solder tabs716, 718, 720, 722 are separated from each other along a width 724 ofcore 702, and in certain embodiments, solder tabs 716, 718, 720, 722 arelaterally adjacent and are at least partially formed along a bottomsurface 726 of core 702, as shown. The outline of solder tabs 716, 718,720, 722 are shown by dashed lines in FIG. 8 where obscured by core 702.FIG. 10 shows a perspective view of windings 712, 714 removed from core702.

Coupled inductor 700 is configured such that an electric current flowingthrough winding 712 from first solder tab 716 to second solder tab 718induces an electric current flowing through winding 714 from thirdsolder tab 720 to fourth solder tab 722. Conversely, an electric currentflowing through winding 714 from third solder tab 720 to fourth soldertab 722 induces an electric current flowing through winding 712 fromfirst solder tab 716 to second solder tab 718. In contrast to prior artstaple winding coupled inductors, coupled inductor 700's configurationmay advantageously allow for coupled inductor 700 to achieve inversemagnetic coupling between windings 712, 714 in multi-phase DC-to-DCconverter applications where all switching power stages are disposed ona common side of inductor 700.

For example, FIG. 11 shows one PCB layout 1100 for use with anembodiment of coupled inductor 700 in a two-phase DC-to-DC converterapplication. Layout 1100 includes pads 1102, 1104, 1106, 1108 forrespectively connecting to solder tabs 716, 718, 720, 722 of coupledinductor 700. Only the outline of coupled inductor 700 is shown in FIG.11 to show the pads of layout 1100. A PCB conductive trace 1110, whichforms part of a first switching node, electrically couples pad 1102 to aswitching circuit 1116, and a PCB conductive trace 1112, which formspart of a second switching node, electrically couples pad 1106 to aswitching circuit 1118. PCB conductive trace 1120, which forms part of acommon node, electrically couples pads 1104, 1108. Layout 1100 is partof, for example, a buck DC-to-DC converter where switching circuits1116, 1118 respectively switch solder tabs 716, 720 between an inputvoltage and ground, and conductive trace 1120 electrically couples to anoutput node. As another example, layout 1100 could be part of a boostconverter DC-to-DC converter where switching circuits 1116, 1118respectively switch solder tabs 716, 720 between an output voltage andground, and conductive trace 1120 electrically couples to an inputvoltage node.

Due to the configuration of coupled inductor 700, traces 1110, 1112 mayextend from a common side 1114 of coupled inductor 700, thereby allowingplacement of both switching circuits 1116, 1118 on the same side ofcoupled inductor 700, as shown in FIG. 11. It should also be appreciatedthat a PCB conductive trace 1120, which connects pads 1104, 1108 to acommon node, is short and wide and has simple, substantially rectangularshape. Furthermore, certain embodiments of coupled inductor 700 may beused with a PCB layout designed for use with coupled inductor 200 ofFIG. 2, thereby potentially allowing for coupled inductor 700 to be usedas a lower cost, lower winding resistance, drop-in replacement forcoupled inductor 200.

Thus, in contrast with many prior coupled inductors, such as coupledinductors 200 and 400 of FIGS. 2 and 4 respectively, coupled inductor700's structure not only promotes low cost, ease of manufacturing, andlow winding resistance; but coupled inductor 700's structure also allowsits use in a DC-to-DC converter where all switching power stages aredisposed in a row on a single side of the coupled inductor, as shown inthe example of FIG. 11. Furthermore, coupled inductor 700's structuremay also allow for its use in a DC-to-DC converter where inductor 700'scommon terminals are electrically coupled by a relatively short and widePCB conductive trace, such as also shown in the example of FIG. 11. Itshould be appreciated that although coupled inductor 700 is discussedwith respect to layout 1100, coupled inductor 700 is not limited to suchlayout. For example, coupled inductor could alternately be configuredsuch that solder tabs 716 and 720 are connected to a common node, andsolder tabs 718 and 722 are connected to respective switching nodes.

FIGS. 12 and 13 show a variation of coupled inductor 700 having widewindings to promote low winding impedance. Specifically, FIG. 12 shows aperspective view, and FIG. 13 shows a top cross-sectional view takenalong line A-A of FIG. 12, of one two-phase coupled inductor 1200, whichis similar to coupled inductor 700, but includes wide windings 1202,1204. The outline of solder tabs of windings 1202, 1204 are shown bydashed lines in FIG. 13 where obscured by a magnetic core 1206, which isshown as transparent in FIG. 12. FIG. 14 shows a perspective view ofwindings 1202, 1204 removed from core 1206. Certain embodiments ofcoupled inductor 1200 may be used with PCB layout 1100 of FIG. 11.

FIG. 15 shows a perspective view of one two-phase coupled inductor 1500,which is similar to coupled inductor 700, but with a different windingconfiguration that allows for a different PCB layout than coupledinductor 700. Coupled inductor 1500 includes a magnetic core 1502, shownas transparent in FIG. 15. Magnetic core 1502 includes a leg 1504 andforms a passageway 1506 from a first side 1508 to a second side 1510 ofcore 1502. Leg 1504 partially defines passageway 1506. FIG. 16 shows atop cross-sectional view of coupled inductor 1500 taken along line A-Aof FIG. 15, and FIG. 17 shows a view of side 1508 of coupled inductor1500.

Coupled inductor 1500 further includes staple style windings 1512, 1514wound at least partially around leg 1504 and through passageway 1506. Afirst end of winding 1512 extends from first side 1508 of core 1502 andforms a first solder tab 1516, and a second end of winding 1512 extendsfrom second side 1510 of core 1502 and forms a second solder tab 1518. Afirst end of winding 1514 extends from first side 1508 of core 1502 andforms a third solder tab 1520, and a second end of winding 1514 extendsfrom second side 1510 of core 1502 and forms a fourth solder tab 1522.Each of solder tabs 1516, 1518, 1520, and 1522 are separated from eachother along a width 1524 of core 1502. In certain embodiments, soldertabs 1516, 1518, 1520, and 1522 are laterally adjacent and are at leastpartially formed along a bottom surface 1526 of core 1502, as shown. Theoutline of solder tabs 1516, 1518, 1520, 1522 are shown by dashed linesin FIG. 16 where obscured by core 1502. FIG. 18 shows a perspective viewof windings 1512, 1514 removed from core 1502.

Coupled inductor 1500 is configured such that an electric currentflowing through winding 1512 from first solder tab 1516 to second soldertab 1518 induces an electric current in winding 1514 flowing from fourthsolder tab 1522 to third solder tab 1520. Conversely, an electriccurrent flowing in winding 1514 from fourth solder tab 1522 to thirdsolder tab 1520 induces an electric current in winding 1512 flowing fromfirst solder tab 1516 to second solder tab 1518. Such configurationadvantageously may allow coupled inductor 1500 to be used in a DC-to-DCconverter where all of the switching power stages are disposed on acommon side of inductor 1500, and adjacent solder tabs 1518 and 1520 areconnected by a common PCB conductive trace.

For example, FIG. 19 shows one PCB layout 1900, which is one possiblePCB layout that may be used with certain embodiments of coupled inductor1500 in a two-phase DC-to-DC converter application. Only the outline ofcoupled inductor 1500 is shown in FIG. 19 to show the pads of layout1900. Layout 1900 includes pads 1902, 1904, 1906, 1908 for respectivelyconnecting to solder tabs 1516, 1518, 1520, 1522 of coupled inductor1500. A PCB conductive trace 1910, which forms part of a switching node,electrically couples pad 1902 to a switching circuit 1916, and a PCBconductive trace 1912, which forms part of another switching node,electrically couples pad 1908 to a switching circuit 1918. Switchingnode traces 1910, 1912 extend from a common side 1914 of coupledinductor 1500, thereby allowing placement of both switching power stages1916, 1918 on the same side of coupled inductor 1500, as shown in FIG.19. Additionally, PCB conductive trace 1920, which forms part of acommon node and electrically couples together pads 1904, 1906, is shortand wide, and has simple, substantially rectangular shape. In contrastto layout 1100 of FIG. 11, both common node pads 1904, 1906 areimmediately adjacent in layout 1900, thereby simplifying layout 1900.Accordingly, coupled inductor 1500 may be preferred to coupled inductor700 in applications where backwards compatibility with layouts forcoupled inductor 200 is not required.

Layout 1900 is part of, for example, a buck DC-to-DC converter whereswitching circuits 1916, 1918 respectively switch solder tabs 1516, 1522between an input voltage and ground, and conductive trace 1920electrically couples to an output node. As another example, layout 1900could be part of a boost DC-to-DC converter where switching circuits1916, 1918 respectively switch solder tabs 1516, 1522 between an outputvoltage and ground, and conductive trace 1920 electrically couples to aninput voltage node.

FIGS. 20 and 21 show a variation of coupled inductor 1500 having widewindings to promote low winding impedance. Specifically, FIG. 20 shows aperspective view, and FIG. 21 shows a top sectional view taken alongline A-A for FIG. 20, of one two-phase coupled inductor 2000, which issimilar to coupled inductor 1500, but includes wide windings 2002, 2004.The outline of solder tabs of windings 2002, 2004 are shown by dashedlines in FIG. 21 where obscured by a magnetic core 2006, which is shownas transparent in FIG. 20. FIG. 22 shows a perspective view of windings2002, 2004 removed from magnetic core 2006. Certain embodiments ofcoupled inductor 2000 may be used with PCB layout 1900 of FIG. 19.

FIG. 23 shows a perspective view of another two-phase coupled inductor2300 including a magnetic core 2302 (shown as transparent in FIG. 23)which forms a passageway (not shown) from a first side 2304 to a secondside 2306 of core 2302. Coupled inductor 2300 further includes staplestyle windings 2308, 2310 wound a least partially around a leg (notshown) extending from first side 2304 to second side 2306 of core 2302.A first end of winding 2308 extends from first side 2304 of core 2302and forms a first solder tab 2312, and a second end of winding 2308extends from second side 2306 of core 2302 and forms a second solder tab2314. A first end of winding 2310 extends from second side 2306 of core2302 and forms a third solder tab 2316, and a second end of winding 2310extends from first side 2304 of core 2302 and forms a fourth solder tab2318. Each of solder tabs 2312, 2314, 2316, and 2318 are separated fromeach other along a width 2320 of core 2302. FIG. 24 shows a perspectiveview of windings 2308, 2310 removed from core 2302.

Coupled inductor 2300 is configured such that an electric currentflowing through winding 2308 from first solder tab 2312 to second soldertab 2314 induces an electric current flowing in winding 2310 from thirdsolder tab 2316 to fourth solder tab 2318. Such configuration allow, forexample, coupled inductor 2300 to be used in a DC-to-DC converter whereall of the power stages are disposed on a common side of inductor 2300.

FIG. 25 shows a perspective view of one two-phase coupled inductor 2500.As discussed below, although coupled inductor 2500 need only include asingle winding, thereby promoting ease of manufacturing and low cost,coupled inductor 2500 can nevertheless be used such that it includes twoeffectively separate windings.

Coupled inductor 2500 includes a magnetic core 2502, shown astransparent in FIG. 25. Magnetic core 2502 includes a leg 2504 and formsa passageway 2506 from a first side 2508 to a second side 2510 of core2502. Leg 2504 partially defines passageway 2506. FIG. 26 shows a topcross-sectional view of coupled inductor 2500 taken along line A-A ofFIG. 25, and FIG. 27 shows first side 2508 of coupled inductor 2500.

Coupled inductor 2500 further includes a staple style winding 2512,which is, for example, a foil winding to minimize the skin effect andthereby promote low AC resistance. Winding 2512 is wound at leastpartially around leg 2504 and through passageway 2506 of core 2502. Afirst end of winding 2512 extends from first side 2508 of core 2502 andforms a first solder tab 2514, and a second end of winding 2512 extendsfrom second side 2510 of core 2502 and forms a second solder tab 2516.An intermediate or center-tapped portion of winding 2512 forms a thirdsolder tab 2518. Thus, single winding 2512 can be utilized in coupledinductor 2500 as two effectively separate windings—a first effectivewinding between first solder tab 2514 and third solder tab 2518, and asecond effective winding between second solder tab 2516 and third soldertab 2518. Each of solder tabs 2514, 2516, 2518 are separated from eachother along a width 2520 of core 2502, and in certain embodiments,solder tabs 2514, 2516, 2518 are laterally adjacent and are at leastpartially formed along a bottom surface 2522 of core 2502, as shown.Solder tabs 2514, 2516, and 2518 are shown by dashed lines in FIG. 26where obscured by core 2502. FIG. 28 shows a perspective view of winding2512 removed from core 2502.

Coupled inductor 2500 is configured such that an electric currentflowing through winding 2512 from first solder tab 2514 to third soldertab 2518 induces an electric current flowing through winding 2512 fromsecond solder tab 2516 to third solder tab 2518. Similarly, a magneticcurrent flowing through winding 2512 from second solder tab 2516 tothird solder tab 2518 induces an electric current in winding 2512flowing from first solder tab 2514 to third solder tab 2518. Suchconfiguration, for example, may allow for coupled inductor 2500 to beused in DC-to-DC converter where all of the power stages are disposed ona common side of inductor 2500.

For example, FIG. 29 shows one PCB layout 2900, which is one possiblelayout that may be used with certain embodiments of coupled inductor2500 in a two-phase DC-to-DC converter application, such as a buckconverter or a boost converter. Only the outline of coupled inductor2500 is shown in FIG. 29 to show the pads of layout 2900. Layout 2900includes pads 2902, 2904, 2906 for respectively connecting to soldertabs 2514, 2516, 2518 of coupled inductor 2500. A PCB conductive trace2908, which forms part of a switching node, electrically couples pad2902 to a switching circuit 2914, and a PCB conductive trace 2910, whichforms part of another switching node, electrically couples pad 2904 to aswitching circuit 2916. Switching circuit traces 2908, 2910 extend froma common side 2912 of coupled inductor 2500, thereby allowing placementof both switching power stages 2914, 2916 on the same side of coupledinductor 2900, as shown in FIG. 29. Additionally, only a single pad 2906connects to a common node, thereby reducing length of common node trace2914 and simplifying layout.

Layout 2900 is part of, for example, a buck DC-to-DC converter whereswitching circuits 2914, 2916 respectively switch solder tabs 2514, 2516between an input voltage and ground, and conductive trace 2914electrically couples to an output node. As another example, layout 2900could be part of a boost DC-to-DC converter where switching circuits2914, 2916 respectively switch solder tabs 2514, 2516 between an outputvoltage and ground, and conductive trace 2914 electrically couples to aninput voltage node.

FIGS. 30 and 31 show a variation of coupled inductor 2500 including awide winding to promote low winding impedance. Specifically, FIG. 30shows a perspective view, FIG. 31 shows a cross sectional view takenalong line A-A of FIG. 30, of one two-phase coupled inductor 3000, whichis similar to coupled inductor 2500 but includes a wide winding 3002.FIG. 32 shows a perspective view of winding 3002 removed from a magneticcore 3004, which is shown as transparent in FIG. 30. FIG. 33 shows a PCBlayout 3300, which is one possible PCB layout that may be used withcertain embodiments of coupled inductor 3000 in a two-phase DC-to-DCconverter application. Layout 3300 includes pads 3302, 3304, 3306 forrespectively connecting to solder tabs 3006, 3008, 3010 (see FIG. 30 andFIG. 31 where outlines of solder tabs are shown with dashed lines whereobscured by core 3004) of winding 3002. Layout 3300 is similar to layout2900 of FIG. 29, but layout 3300 includes a wider conductive trace 3308connecting to a common node, thereby promoting even lower impedance ofthe common node.

FIG. 34 shows one two-phase coupled inductor 3400. Coupled inductor 3400includes a magnetic core 3402 including a leg (not shown) and forming apassageway (not shown) from a first side 3404 to a second side 3406 ofcore 3402. Coupled inductor 3400 further includes a staple style winding3408, which is, for example, a foil winding to minimize the skin effectand thereby promote low winding impedance. Winding 3408 is wound aroundthe leg of core 3402 and through the passageway of core 3402. A firstend of winding 3408 extends from first side 3404 of core 3402 and formsa first solder tab 3410, and a second end of winding 3408 extends fromsecond side 3406 of core 3402 and forms a second solder tab 3412. Anintermediate or center-tapped portion of winding 3408 forms a thirdsolder tab 3414. In certain embodiments, solder tabs 3410, 3412, 3414are at least partially formed along a bottom surface 3416 of core 3402,as shown. FIG. 35 shows a perspective view of winding 3408 removed fromcore 3402.

Coupled inductor 3400 is configured such that an electric currentflowing through winding 3408 from first solder tab 3410 to third soldertab 3414 induces an electric current flowing through winding 3408 fromsecond solder tab 3412 to third solder tab 3414. Similarly, an electriccurrent flowing through winding 3408 from second solder tab 3412 tothird solder tab 3414 induces a current in winding 3408 flowing fromfirst solder tab 3410 to third solder tab 3414. Similar to coupledinductors 2500 and 3000 of FIGS. 25 and 30 respectively, althoughcoupled inductor 3400 need only include a single winding, therebypromoting ease of manufacturing and low cost, coupled inductor 3400 cannevertheless be used such that it includes two effectively separatewindings.

FIG. 36 shows a perspective view of one two-phase coupled inductor 3600.Coupled inductor 3600 includes a magnetic core 3602 including a leg 3604and forming a passageway 3606 extending from a first side 3608 to asecond side 3610 of core 3602. Leg 3604 partially defines passageway3606. FIG. 37 shows a top cross-sectional view of coupled inductor 3600taken along line A-A of FIG. 36, and FIG. 38 shows side 3608 of coupledinductor 3600.

Coupled inductor 3600 further includes staple style windings 3612, 3614which are, for example, foil windings. Each winding 3612, 3614 is woundat least partially through passageway 3606. Windings 3612, 3614 alsocross each other in passageway 3606, which advantageously enablescoupled inductor 3600 to achieve inverse magnetic coupling in a DC-to-DCconverter application where each power stage is disposed on a commonside of the coupled inductor.

A first end of winding 3612 extends from first side 3608 of magneticcore 3602 and forms a first solder tab 3616, and a second end of winding3612 extends from second side 3610 of core 3602 and forms a secondsolder tab 3618. A first end of winding 3614 extends from first side3608 of magnetic core 3602 and forms a third solder tab 3620, and asecond end of winding 3614 extends from second side 3610 of core 3602and forms a fourth solder tab 3622. In certain embodiments, solder tabs3616, 3618, 3620, 3622 are at least partially formed along a bottomsurface 3624 of core 3602, as shown. The outlines of solder tabs 3616,3618, 3620, 3622 are shown by dashed lines in FIG. 37 where obscured bycore 3602. FIG. 39 shows a perspective view of windings 3612, 3614 andtheir relative positions but with magnetic core 3602 removed. Windings3612 and 3614 are insulated at least where they cross in passageway 3606by an insulator such as insulating tape or varnish.

The fact that windings 3612, 3614 cross in passageway 3606 results inwindings 3612, 3614 being magnetically coupled such that a currentflowing through winding 3612 from first solder tab 3616 to second soldertab 3618 induces an electric current in winding 3618 flowing from thirdsolder tab 3620 to fourth solder tab 3622. Therefore, coupled inductorcan be used, for example, in a DC-to-DC converter where solder tabs onone side of core 3602 are connecting to respective switching powerstages and solder tabs on another side of the core 3602 are connected toa common node.

For example, FIG. 40 shows one PCB layout 4000, which is one possiblelayout that may be used with coupled inductor 3600 in a two-phaseDC-to-DC converter, such as a buck converter or a boost converter.Layout 4000 includes pads 4002, 4004, 4006, 4008 for respectivelycoupling to solder tabs 3616, 3618, 3620, 3622 of coupled inductor 3600.Only the outline of coupled inductor 3600 is shown in FIG. 40 to showthe pads of layout 4000. PCB conductive trace 4010, which forms part ofa switching node, electrically couples pad 4002 to a switching circuit4012. PCB conductive trace 4014, which forms part of another switchingnode, electrically couples pad 4006 to a switching circuit 4016. A PCBconductive trace 4018, which forms part of a common node, electricallycouples pads 4004, 4008. Switching circuits 4012, 4016 are located on acommon side 4020 in layout 4000. Additionally, conductive trace 4018 isshort, wide, and has a simple rectangular shape, thereby promoting lowimpedance of trace 4018 and its manufacturability.

Layout 4000 is part of, for example, a buck DC-to-DC converter whereswitching circuits 4012, 4016 respectively switch solder tabs 3616, 3620between an input voltage and ground, and conductive trace 4018electrically couples to an output node. As another example, layout 1900could be part of a boost DC-to-DC converter where switching circuits4012, 4016 respectively switch solder tabs 3616, 3620 between an outputvoltage and ground, and conductive trace 4018 electrically couples to aninput voltage node.

FIGS. 41 and 42 show a variation of coupled inductor 3600 including widewindings to promote low winding impedance. Specifically, FIG. 41 shows aperspective view, and FIG. 42 shows a top cross-sectional view takenalong line A-A of FIG. 41, of one two-phase coupled inductor 4100, whichis similar to coupled inductor 3600, but has a different windingconfiguration. In particular, coupled inductor 4100 includes a magneticcore 4102 (shown as transparent in FIG. 41) including a leg 4104 andforming a passageway 4106 extending from a first side 4108 to a secondside 4110 of core 4102. Leg 4104 partially defines passageway 4106.Coupled inductor 4100 further includes staple style windings 4112, 4114that are, for example, foil windings. Each winding 4112, 4114 is woundat least partially through passageway 4106, and windings 4112, 4114cross in passageway 4106. Windings 4112, 4114 are insulated at leastwhere they cross in passageway 4106. One or more of areas 4202, 4204(see FIG. 42) between windings 4112, 4114 in passageway 4106 arepartially or fully filled with magnetic material to increase leakageinductance values of windings 4112, 4114 when used in a circuit, such asa DC-to-DC converter. As known in the art, coupled inductor leakageinductance values must be sufficiently large in multi-phase DC-to-DCconverter applications to limit ripple current magnitude.

FIG. 43 shows a perspective view of windings 4112, 4114 separated fromeach other and separated from core 4102. Windings 4112, 4114 arestacked, however, when installed in inductor 4100, such as suggested byarrow 4302. FIG. 44 shows a perspective view of windings 4112, 4114 whenstacked but separated from 4102. Although winding 4114 is shown stackedon top of winding 4112, the order of stacking could be changed such thatwinding 4112 is stacked on winding 4114. Certain embodiments of coupledinductor 4100 may be used with PCB layout 4000 of FIG. 40.

FIG. 45 shows a perspective view and FIG. 46 shows a top view of onetwo-phase coupled inductor 4500. Coupled inductor 4500 includes amagnetic core 4502, shown as transparent in FIG. 45, including a firstside 4504 opposite a second side 4506, a third side 4508 opposite afourth side 4510, and a fifth side 4512 opposite a sixth side 4514. FIG.47 shows a transparent perspective view of core 4502 without windings.Fifth side 4512 connects first side 4504 to the third side 4508 andforms an obtuse angle 4602 with the first side 4504. Fifth side 4512also forms an obtuse angle 4604 with the third side 4508. Sixth side4514 connects second side 4506 to fourth side 4510 and forms an obtuseangle 4606 with second side 4506. Sixth side 4514 also forms an obtuseangle 4608 with fourth side 4510. First side 4504 joins fourth side 4510at an obtuse angle 4610, and second side 4506 joins third side 4508 atan obtuse angle 4612. Magnetic core 4502 forms a passageway 4516extending through core 4502 from fifth side 4512 to sixth side 4514, andpassageway 4516 is partially defined by a leg 4518 of magnetic core4502.

Coupled inductor 4500 further includes windings 4520, 4522, which arewound through passageway 4516 and at least partially around leg 4518. Afirst end of winding 4520 extends from fifth side 4512 of core 4502 andforms a first solder tab 4524, and a second end of winding 4520 extendsfrom sixth side 4514 of core 4502 and forms a second solder tab 4526. Afirst end of winding 4522 extends from fifth side 4512 of core 4502 andforms a third solder tab 4528, and a second end of winding 4522 extendsfrom sixth side 4514 of core 4502 and forms a fourth solder tab 4530.Coupled inductor 4500 is configured such that a current flowing throughwinding 4520 from second solder tab 4526 to first solder tab 4524induces an electric current flowing through winding 4522 from thirdsolder tab 4528 to fourth solder tab 4530. Similarly, an electriccurrent flowing through winding 4522 from third solder tab 4528 tofourth solder tab 4530 induces an electric current flowing throughwinding 4520 from second solder tab 4526 to first solder tab 4524.

FIG. 48 shows a perspective view of windings 4520, 4522 separate fromcore 4502. Some or all of passageway 4516 between windings 4520, 4522 isoptionally partially or completely filled with magnetic material toincrease leakage inductance values of windings 4520, 4522 when used in acircuit.

FIG. 49 shows a top cross sectional view of an embodiment of coupledinductor 4500 taken along line A-A of FIG. 45 and installed on onepossible DC-to-DC converter PCB layout 4900. Layout 4900, for example,forms part of a buck converter or a boost converter. However, coupledinductor 4500 is not limited to PCB layout 4900. Layout 4900 includesPCB pads 4902, 4904, 4906, 4908 for respectively coupling to solder tabs4524, 4526, 4528, 4530 of coupled inductor 4900. The outlines of soldertabs 4524, 4526, 4528, and 4530 are shown by dashed lines in FIG. 49where obscured by core 4502. A PCB conductive trace 4910, which formspart of a switching node, electrically couples pad 4904 to a switchingcircuit 4916, and a PCB conductive trace 4912, which forms part ofanother switching node, electrically couples pad 4906 to a switchingcircuit 4918. Switching node traces 4910, 4912 extend from a common side4914 of coupled inductor 4500, thereby allowing placement of bothswitching power stages 4916, 4918 on the same side of coupled inductor4900, as shown in FIG. 49. PCB conductive trace 4920, which forms partof a common node, electrically couples pads 4902, 4908. It should beappreciated that PCB conductive trace 4920 is wide, thereby promotinglow impedance on the common node. Furthermore, trace 4920 has a simple,rectangular shape, thereby promoting manufacturing robustness of theFIG. 49 layout.

Layout 4900 is part of, for example, a buck DC-to-DC converter whereswitching circuits 4916, 4918 respectively switch solder tabs 4526, 4528between an input voltage and ground, and conductive trace 4920electrically couples to an output node. As another example, layout 4900could be part of a boost DC-to-DC converter where switching circuits4916, 4918 respectively switch solder tabs 4526, 4528 between an outputvoltage and ground, and conductive trace 4920 electrically couples to aninput voltage node.

FIG. 50 shows a perspective view of one two-phase coupled inductor 5000.Coupled inductor 5000 includes a magnetic core 5002 (shown astransparent in FIG. 50) including a first side 5004 and a second side5006 opposite first side 5004. Magnetic core 5002 forms a passageway5008 extending from first side 5004 to second side 5006. FIG. 51 showsside 5004 of coupled inductor 5000. Passageway 5008 is partially definedby first and second opposing surfaces 5010, 5012, and a leg 5014connects opposing surfaces 5010, 5012.

Coupled inductor 5000 further includes windings 5016, 5018 that are, forexample, foil windings to promote low impedance and low manufacturingcost. Winding 5016 is wound at least partially around leg 5014 inpassageway 5008. A first end of winding 5016 extends from first side5004 of core 5002 and forms a first solder tab 5020, and a second end ofwinding 5016 extends from first side 5004 of core 5002 and forms asecond solder tab 5022. A first end of winding 5018 extends from secondside 5006 of core 5002 and forms a third solder tab 5024, and a secondend of winding 5018 extends from second side 5006 of core 5002 and formsa fourth solder tab 5026. Solder tabs 5020, 5022, 5024, 5026 are, forexample, disposed along a bottom surface 5028 of core 5002.

Coupled inductor 5000 is configured such that a current flowing throughwinding 5016 from first solder tab 5020 to second solder tab 5022induces a current flowing through winding 5018 from third solder tab5024 to fourth solder tab 5026. Similarly, a current flowing throughwinding 5018 from third solder tab 5024 to fourth solder tab 5026induces a current flowing through winding 5016 from first solder tab5020 to second solder tab 5022.

FIG. 52 shows a transparent perspective view of core 5002 with windings5016, 5018 removed. FIG. 53 shows a perspective view of windings 5016,5018 separated from core 5002 and from each other. However, windings5016, 5018 at least partially overlap when installed in coupled inductor5002. FIG. 54 shows a perspective view of windings 5016, 5018 separatedfrom core 5002 but overlapping as they would when installed in coupledinductor 5000. Although winding 5016 is shown stacked on winding 5018,winding 5018 alternately is stacked on winding 5016. Windings 5016, 5018are insulated at least where they overlap, such as by an insulating tapeor varnish, or other insulating coating, on one or more of windings5016, 5018.

Windings 5016, 5018 are shown as rectangular shaped foil windings, suchas shown in FIGS. 50 and 53-54. Rectangular shaped foil windings can bestamped into shape and therefore are typically easier to assemble withmagnetic cores than helical windings. Foil windings are also lesssusceptible to the skin effect than cylindrical windings, therebypromoting low winding impedance. However, the configuration of winding5016, 5018 could be varied. For example, FIG. 55 shows a top crosssectional view of coupled inductor 5500 installed on one possibleDC-to-DC converter PCB layout 5501. Layout 5501, for example, forms partof a buck converter or a boost converter. Coupled inductor 5500 issimilar to coupled inductor 5000, but coupled inductor 5500 includeshelical windings 5502, 5504 instead of stamped rectangular windings anda rounded leg 5506 instead of a rectangular leg connecting opposingpassageway surfaces.

The FIG. 55 layout includes PCB pads 5508, 5510 for coupling torespective solder tabs of winding 5502 and PCB pads 5512, 5514 forcoupling to respective solder tabs of winding 5504. A PCB conductivetrace 5516, which forms part of a switching node, electrically couplespad 5508 to a switching circuit 5522, and a PCB conductive trace 5518,which forms part of another switching node, electrically couples pad5512 to a switching circuit 5524. Switching node traces 5516, 5518extend from a common side 5520 of coupled inductor 5500, therebyallowing placement of both switching circuits 5522, 5524 on the sameside of coupled inductor 5500, as shown in FIG. 55. It should also benoted that a PCB conductive trace 5526, which forms part of a commonnode and electrically couples together pads 5510, 5514, is short andwide, thereby promoting low impedance on the common node. Furthermore,trace 5526 and has simple, rectangular shape, thereby promotingmanufacturing robustness of the FIG. 55 layout. Certain embodiments ofcoupled inductor 5000 of FIG. 50 could also be used with the PCB layoutof FIG. 55.

Layout 5501 is part of, for example, a buck DC-to-DC converter whereswitching circuits 5522, 5524 respectively switch a solder tab ofwindings 5502, 5504 between an input voltage and ground, and conductivetrace 5526 electrically couples to an output node. As another example,layout 5501 could be part of a boost DC-to-DC converter where switchingcircuits 5522, 5524 respectively switch a solder tab of windings 5502,5504 between an output voltage and ground, and conductive trace 5526electrically couples to an input voltage node.

FIG. 56 shows another variation of coupled inductor 5000 of FIG. 50. Inparticular, FIG. 56 shows a perspective view of one two-phase coupledinductor 5600, which is similar to coupled inductor 5000, but coupledinductor 5600 includes windings 5602, 5604 extending from a first side5606 of a magnetic core 5608 (shown as transparent in FIG. 56) to asecond side 5610 of core 5608. FIG. 57 shows first side 5606 of coupledinductor 5600. Winding 5602 includes an intermediate portion 5612disposed along second side 5610 of magnetic core 5608, and winding 5604includes an intermediate portion 5614 disposed along first side 5606 ofcore 5608. Intermediate portions 5612, 5614 may help hold inductor 5600together, thereby promoting its mechanical robustness. Additionally, thefact that intermediate portions 5612, 5614 are disposed outside of apassageway 5616 of magnetic core 5608 allows for a leg 5618 connectingopposing portions 5620, 5622 of passageway 5616 to occupy a largeportion of passageway 5616, thereby increasing the size of leg 5618 anddecreasing core losses in leg 5618. For example, leg 5618 may extendfrom first side 5606 to second side 5610 of core 5608, as shown in FIG.56.

FIG. 58 shows a top cross sectional view of coupled inductor 5600 takenalong line A-A of FIG. 56 and installed on a PCB layout similar to thatof FIG. 55. FIG. 59 shows a transparent perspective view of magneticcore 5608 with windings 5602, 5604 removed. FIG. 60 shows a perspectiveview of windings 5602, 5604 removed from magnetic core 5608 andseparated from each other, and FIG. 61 shows a perspective view ofwindings 5602, 5604 overlapping as they would when installed in coupledinductor 5600. Although winding 5602 is shown stacked on winding 5604,the stacking order could be reversed. Additionally, the configuration ofintermediate portions 5612, 5614 could be varied, for example, such thatintermediate portions 5612, 5614 extend in a different directionrelative to passageway 5616. For example, intermediate portions 5612,5614 could be alternately configured such that intermediate portion 5612extends downward with respect to passageway 5616, and intermediateportion 5614 extends upward with respect to passageway 5616.

FIG. 62 shows a perspective view of one two-phase coupled inductor 6200including a magnetic core 6202 including a first side 6204 and anopposite second side 6206. Magnetic core 6202 further includes endmagnetic elements 6208, 6210 and legs 6212, 6214 disposed between andconnecting end magnetic elements 6208, 6210. Magnetic core 6202 forms apassageway 6216 extending through core 6202 from first side 6204 tosecond side 6206, and passageway 6216 is partially defined by legs 6212,6214. Magnetic core 6202 further includes a bottom surface 6218, whichfor example, connects first and second sides 6204, 6206. In certainembodiments, bottom surface 6218 is at least substantially orthogonal tofirst and second sides 6204, 6206.

Coupled inductor 6200 further includes winding 6220 wound around leg6212 and through passageway 6216, as well as winding 6222 wound aroundleg 6214 and through passageway 6216. A first end of winding 6220extends from first side 6204 of core 6202 and electrically couples to afirst solder tab 6224, and a second end of winding 6220 extends fromsecond side 6206 of core 6202 and electrically couples to a secondsolder tab 6226. A first end of winding 6222 extends from first side6204 of core 6202 and electrically couples to a third solder tab 6228,and a second end of winding 6222 extends from second side 6206 of core6202 and electrically couples to a fourth solder tab 6230. Solder tabs6224, 6226, 6228, 6230 are, for example, disposed along bottom surface6218, such as shown in FIG. 62. Some or all of passageway 6216 betweenwindings 6220, 6222 is optionally partially or fully filled withmagnetic material to increase leakage inductance values of windings6220, 6222 when used in a circuit.

Windings 6220 and 6222 are wound about their respective legs 6212, 6214such that a current flowing through winding 6220 from second solder tab6226 to first solder tab 6224 induces an electric current flowingthrough winding 6222 from fourth solder tab 6230 to third solder tab6228. Similarly, a current flowing through second winding 6222 fromfourth solder tab 6230 to third solder tab 6228 induces a currentflowing through first winding 6220 from second solder tab 6226 to firstsolder tab 6224. Such feature advantageously enables coupled inductor6200 to be used, for example, in a DC-to-DC converter where allswitching power stages are disposed on a common side of coupled inductor6200. For example, FIG. 63 shows a top cross sectional view of onecoupled inductor 6300 installed on a PCB layout 6302. Layout 6302 is,for example, a buck DC-to-DC converter or a boost DC-to-DC converterlayout. Coupled inductor 6300 is similar to coupled inductor 6200 ofFIG. 62, but coupled inductor 6300 includes cylindrical legs 6304, 6306instead of rectangular legs.

Layout 6302 includes pads 6308, 6310, 6312, 6314 for respectivelycoupling to solder tabs 6224, 6226, 6228, 6230 of coupled inductor 6300.A PCB conductive trace 6316, which forms part of a switching node,electrically couples pad 6310 to a switching circuit 6322, and a PCBconductive trace 6318, which forms part of a switching node,electrically couples pad 6314 to a switching circuit 6324. Switchingtraces 6316, 6318 extend from a common side 6320 of coupled inductor6300, thereby allowing placement of both switching circuits 6322, 6324on the same side of coupled inductor 6300, as shown in FIG. 63. Itshould also be noted that a PCB conductive trace 6326, which forms partof a common node and electrically couples together pads 6308, 6312, isshort and wide, thereby promoting low impedance on the common node.Furthermore, trace 6326 has simple, rectangular shape, thereby promotingmanufacturing robustness of layout 6302. Certain embodiments of coupledinductor 6200 of FIG. 62 could also be used layout 6302.

Layout 6302 is part of, for example, a buck DC-to-DC converter whereswitching circuits 6322, 6324 respectively switch solder tabs 6226, 6230between an input voltage and ground, and conductive trace 6326electrically couples to an output node. As another example, layout 6302could be part of a boost DC-to-DC converter where switching circuits6322, 6324 respectively switch solder tabs 6226, 6230 between an outputvoltage and ground, and conductive trace 6326 electrically couples to aninput voltage node.

As discussed above, one possible use of the coupled inductors disclosedherein is in switching power supplies, such as in switching DC-to-DCconverters. Accordingly, the magnetic cores of the coupled inductorsdiscussed herein are typically formed of a magnetic material (e.g., aferrite material or a powdered iron material) that exhibits a relativelylow core loss at high switching frequencies (e.g., at least 20 KHz) thatare common in switching power supplies.

For example, FIG. 64 schematically shows one power supply 6400, which isone possible application of the inductors discussed herein. Power supply6400 includes a PCB 6402 for supporting and electrically connectingcomponents of power supply 6400. PCB 6402 could alternately be replacedwith a number of separate, but electrically interconnected, PCBs.

Power supply 6400 is shown as including two phases 6404, where eachphase includes a respective switching circuit 6406 and a winding 6408 ofa two-phase coupled inductor 6410. However, power supply 6400 could bemodified to have a different number of phases 6404, such as four phases,where a first pair of phases utilizes windings of a first two-phasecoupled inductor, and a second pair of phases utilizes windings of asecond two-phase coupled inductor. Examples of two-phase coupledinductor 6410 include coupled inductor 700 (FIG. 7), coupled inductor1200 (FIG. 12), coupled inductor 1500 (FIG. 15), coupled inductor 2000(FIG. 20), coupled inductor 2300 (FIG. 23), coupled inductor 2500 (FIG.25), coupled inductor 3000 (FIG. 30), coupled inductor 3400 (FIG. 34),coupled inductor 3600 (FIG. 36), coupled inductor 4100 (FIG. 41),coupled inductor 4500 (FIG. 45), coupled inductor 5000 (FIG. 50),coupled inductor 5500 (FIG. 55), coupled inductor 5600 (FIG. 56),coupled inductor 6200 (FIG. 62), and coupled inductor 6300 (FIG. 63).

Each winding 6408 has a respective first terminal 6412 and a respectivesecond terminal 6414. First and second terminals 6412, 6414, forexample, form surface mount solder tabs suitable for surface mountsoldering to PCB 6402. For example, in an embodiment where coupledinductor 6410 is an embodiment of coupled inductor 700 (FIG. 7), firstterminal 6412(1) represents solder tab 718, second terminal 6414(1)represents solder tab 716, first terminal 6412(2) represents solder tab722, and second terminal 6414(2) represents solder tab 720. Coupledinductor 6410 is configured such that it has inverse magnetic coupling.Therefore, an electric current flowing through winding 6408(1) fromsecond terminal 6414(1) to first terminal 6412(1) induces an electriccurrent in winding 6408(2) flowing from second terminal 6414(2) to firstterminal 6412(2). Similarly, a current flowing through winding 6408(2)from second terminal 6412(2) to first terminal 6412(2) induces a currentflowing through winding 6408(1) flowing from second terminal 6414(1) tofirst terminal 6412(1).

Each first terminal 6412 is electrically connected to a common firstnode 6416, such as via a PCB trace 6418. Each second terminal 6414 iselectrically connected to a respective switching circuit 6406, such asby a respective PCB trace 6420. Switching circuits 6406 are configuredand arranged to switch second terminal 6414 of their respective winding6408 between at least two different voltage levels. Controller 6422controls switching circuits 6406, and controller 6422 optionallyincludes a feedback connection 6424, such as to first node 6416. Firstnode 6416 optionally includes a filter 6426.

Power supply 6400 typically has a switching frequency, the frequency atwhich switching circuits 6406 switch, of at least about 20 kHz, suchthat sound resulting from switching is above a frequency rangeperceivable by humans. Operating switching power supply 6400 at a highswitching frequency (e.g., at least 20 kHz) instead of at a lowerswitching frequency may also offer advantages such as (1) an ability touse smaller energy storage components (e.g., coupled inductor 6410 andfilter capacitors), (2) smaller ripple current and ripple voltagemagnitude, and/or (3) faster converter transient response. To enableefficient operation at high switching frequencies, the one or moremagnetic materials forming a magnetic core 6428 of coupled inductor 6410are typically materials having relatively low core losses at highfrequency operation, such as ferrite materials or powdered ironmaterials.

In some embodiments, controller 6422 controls switching circuits 6406such that each switching circuit 6406 operates out of phase from eachother switching circuit 6406. Stated differently, in such embodiments,the switched waveform provided by each switching circuit 6406 to itsrespective second terminal 6414 is phase shifted with respect to theswitched waveform provided by each other switching circuit 6406 to itsrespective second terminal 6414. For example, in certain embodiments ofpower supply 6400, switching circuit 6406(1) provides a switchedwaveform to second terminal 6414(1) that is about 180 degrees out ofphase with a switched waveform provided by switching circuit 6406(2) tosecond terminal 6414(2).

Power supply 6400 can be configured to have a variety of configurations.For example, switching circuits 6406 may switch their respective secondterminals 6414 between an input voltage node (not shown) and ground,such that power supply 6400 is configured as a buck converter, firstnode 6416 is an output voltage node, and filter 6426 is an outputfilter. In this example, each switching circuit 6406 includes at leastone high side switching device and at least one catch diode, or at leastone high side switching device and at least one low side switchingdevice. In the context of this document, a switching device includes,but is not limited to, a bipolar junction transistor, a field effecttransistor (e.g., an N-channel or P-channel metal oxide semiconductorfield effect transistor, a junction field effect transistor, or a metalsemiconductor field effect transistor), an insulated gate bipolarjunction transistor, a thyristor, or a silicon controlled rectifier.

In embodiments where power supply 6400 is a DC-to-DC converter, powersupply 6400 may utilize one of the PCB layouts discussed above, such asPCB layout 1100 (FIG. 11), 1900 (FIG. 19), 2900 (FIG. 29), 3300 (FIG.33), 4000 (FIG. 40), 4900 (FIG. 49), 5501 (FIG. 55), or 6302 (FIG. 63).For example, if power supply 6400 is a buck converter using inductor 700with PCB layout 1100, switching circuits 1116, 1118 of layout 1100correspond to switching circuits 6406(1), 6406(2) of power supply 6400,and switching node traces 1110, 1112 of layout 1100 correspond to traces6420(1), 6420(2) of power supply 6400.

As another example, power supply 6400 can be configured as a boostconverter such that first node 6416 is an input power node, andswitching circuits 6406 switch their respective second terminal 6414between an output voltage node (not shown) and ground. Additionally,power supply 6400 can be configured, for example, as a buck-boostconverter such that first node 6416 is a common node, and switchingcircuits 6406 switch their respective second terminal 6414 between anoutput voltage node (not shown) and an input voltage node (not shown).

Furthermore, as yet another example, power supply 6400 may form anisolated topology. For example, each switching circuit 6406 may includea transformer, at least one switching device electrically coupled to thetransformer's primary winding, and a rectification circuit coupledbetween the transformer's secondary winding and the switching circuit'srespective second terminal 6414. The rectification circuit optionallyincludes at least one switching device to improve efficiency.

Changes may be made in the above methods and systems without departingfrom the scope hereof. For example, although many of the embodimentsdisclosed above are illustrated with rectangular shaped magnetic cores,the magnetic core shapes could be varied. For example, one or more edgesof the magnetic cores could be rounded, or one or more rectangularmagnetic core elements could be replaced with cylindrical magneticelements. As another example, although windings are generally shownabove as single turn windings, one or more of the windings couldalternately be multi turn windings. As yet another example, although theembodiments shown above are generally shown with solder tabs forelectrically coupling windings to PCB pads, the solder tabs could bereplaced with another type of terminal, such as through-hole pins. Itshould thus be noted that the matter contained in the above descriptionand shown in the accompanying drawings should be interpreted asillustrative and not in a limiting sense. The following claims areintended to cover generic and specific features described herein, aswell as all statements of the scope of the present method and system,which, as a matter of language, might be said to fall therebetween.

1. A two-phase coupled inductor, comprising: a magnetic core including a first side and a second side opposite the first side, the magnetic core forming a passageway extending through the core from the first side to the second side, the passageway partially defined by a first leg of the magnetic core; a first winding wound at least partially around the first leg and through the passageway, a first end of the first winding extending from the first side of the core and forming a first solder tab, a second end of the first winding extending from the second side of the core and forming a second solder tab; and a second winding wound at least partially around the first leg and through the passageway, a first end of the second winding extending from the second side of the core and forming a third solder tab, a second end of the second winding extending from the first side of the core and forming a fourth solder tab; the first, second, third, and fourth solder tabs being separated from each other along a width of the magnetic core; wherein an electric current flowing through the first winding from the first solder tab to the second solder tab induces an electric current in the second winding flowing from the third solder tab to the fourth solder tab.
 2. The two-phase coupled inductor of claim 1, the first, second, third, and fourth solder tabs being at least partially laterally adjacent to each other along the width of the magnetic core.
 3. The two-phase coupled inductor of claim 1, the third solder tab being disposed between the second and fourth solder tabs along the width of the magnetic core.
 4. The two-phase coupled inductor of claim 1, the fourth solder tab being disposed between the second and third solder tabs along the width of the magnetic core.
 5. A two-phase coupled inductor, comprising: a magnetic core including a first side and a second side opposite the first side, the magnetic core forming a passageway extending through the core from the first side to the second side, the passageway partially defined by a first leg of the magnetic core; and a first winding forming at least two turns around the first leg and wound through the passageway, a first end of the first winding extending from the first side of the core and forming a first solder tab along a bottom surface of the coupled inductor, a second end of the first winding extending from the second side of the core and forming a second solder tab along the bottom surface of the coupled inductor, and an intermediate portion of the first winding between the first and second ends of the first winding forming a third solder tab along the bottom surface of the coupled inductor; the first, second, and third solder tabs being separated from each other along a width of the magnetic core; wherein an electric current flowing through the first winding from the first solder tab to the third solder tab induces an electric current in the first winding flowing from the second solder tab to the third solder tab.
 6. A two-phase coupled inductor, comprising: a magnetic core including a first side opposite a second side, the magnetic core forming a passageway extending through the core from the first side to the second side, the passageway partially defined by a first leg of the magnetic core; a first winding wound at least partially around the first leg and through the passageway, a first end of the first winding extending from the first side of the core and forming a first solder tab, a second end of the first winding extending from the second side of the core and forming a second solder tab; and a second winding wound at least partially around the first leg and through the passageway, a first end of the second winding extending from the first side of the core and forming a third solder tab, a second end of the second winding extending from the second side of the core and forming a fourth solder tab; wherein the first winding crosses the second winding within the passageway.
 7. A two-phase coupled inductor, comprising: a magnetic core including a first side opposite a second side, a third side opposite a fourth side, and a fifth side opposite a sixth side, the fifth side connecting the first side to the third side and forming an obtuse angle with the first side and an obtuse angle with the third side, the sixth side connecting the second side to the fourth side and forming an obtuse angle with the second side and an obtuse angle with the fourth side, the magnetic core forming a passageway extending through the core from the fifth side to the sixth side, the passageway partially defined by a first leg of the magnetic core; a first winding wound at least partially around the first leg and through the passageway, a first end of the first winding extending from the fifth side of the core and forming a first solder tab, a second end of the first winding extending from the sixth side of the core and forming a second solder tab; and a second winding wound at least partially around the first leg and through the passageway, a first end of the second winding extending from the fifth side of the core and forming a third solder tab, a second end of the second winding extending from the sixth side of the core and forming a fourth solder tab.
 8. A two-phase coupled inductor, comprising: a magnetic core including a first side opposite a second side, the magnetic core forming a passageway extending through the core from the first side to the second side, the passageway partially defined by first and second opposing surfaces, the magnetic core including a first leg connecting the first and second surfaces within the passageway; a first winding wound at least partially around the first leg, a first end of the first winding extending from the first side of the core and forming a first solder tab, a second end of the first winding extending from the first side of the core and folining a second solder tab; and a second winding wound at least partially around the first leg, a first end of the second winding extending from the second side of the core and forming a third solder tab, a second end of the second winding extending from the second side of the core and forming a fourth solder tab.
 9. The two-phase coupled inductor of claim 8, the first winding extending through the passageway from the first side to the second side of the core, the second winding extending through the passageway from the second side to the first side of the core.
 10. A power supply, comprising: a printed circuit board; a two-phase coupled inductor affixed to the printed circuit board, the two-phase coupled inductor including: a magnetic core including a first side and a second side opposite the first side, the magnetic core forming a passageway extending through the core from the first side to the second side, the passageway partially defined by a first leg of the magnetic core; a first winding wound at least partially around the first leg and through the passageway, a first end of the first winding extending from the first side of the core and forming a first solder tab, a second end of the first winding extending from the second side of the core and forming a second solder tab, and a second winding wound at least partially around the first leg and through the passageway, a first end of the second winding extending from the second side of the core and forming a third solder tab, a second end of the second winding extending from the first side of the core and forming a fourth solder tab, the first, second, third, and fourth solder tabs being separated from each other along the width of the magnetic core, wherein an electric current flowing through the first winding from the first solder tab to the second solder tab induces an electric current flowing through the second winding from the third solder tab to the fourth solder tab; a first switching circuit affixed to the printed circuit board and electrically coupled to the first solder tab, the first switching circuit configured to switch the first solder tab between at least two different voltage levels; a second switching circuit affixed to the printed circuit board and electrically coupled to the third solder tab, the second switching circuit configured to switch the third solder tab between at least two different voltage levels; and a conductive trace affixed to the printed circuit and electrically coupling together the second and fourth solder tabs.
 11. The power supply of claim 10, the first and second switching circuits being disposed along the second side of the magnetic core.
 12. The power supply of claim 11, each of the first and second switching circuits configured to switch at a frequency of at least 20 kilohertz, and the magnetic core being formed of a material selected from the group consisting of a ferrite material and a powdered iron material.
 13. The power supply of claim 10, the fourth solder tab being disposed between the second and third solder tabs along the width of the magnetic core.
 14. The power supply of claim 13, the conductive trace electrically coupled to an output node of the power supply.
 15. A power supply, comprising: a printed circuit board; a two-phase coupled inductor affixed to the printed circuit board, the two-phase coupled inductor including: a magnetic core including a first side and a second side opposite the first side, the magnetic core forming a passageway extending through the core from the first side to the second side, the passageway partially defined by a first leg of the magnetic core, and a first winding forming at least two turns and wound around the first leg and through the passageway, a first end of the first winding extending from the first side of the core and forming a first solder tab along a bottom surface of the coupled inductor, a second end of the first winding extending from the second side of the core and forming a second solder tab along the bottom surface of the coupled inductor, and an intermediate portion of the first winding between the first and second ends of the first winding forming a third solder tab along the bottom surface of the coupled inductor, the first, second, and third solder tabs being separated from each other along a width of the magnetic core, wherein an electric current flowing through the first winding from the first solder tab to the third solder tab induces an electric current in the first winding flowing from the second solder tab to the third solder tab; a first switching circuit affixed to the printed circuit board and electrically coupled to the first solder tab, the first switching circuit configured to switch the first solder tab between at least two different voltage levels; a second switching circuit affixed to the printed circuit board and electrically coupled to the second solder tab, the second switching circuit configured to switch the second solder tab between at least two different voltage levels; and a conductive trace affixed to the printed circuit and electrically coupled to the third tab and extending from the first side of the magnetic core.
 16. The power supply of claim 15, each of the first and second switching circuits being disposed along the second side of the magnetic core.
 17. The power supply of claim 16, each of the first and second switching circuits configured to switch at a frequency of at least 20 kilohertz, and the magnetic core being formed of a material selected from the group consisting of a ferrite material and a powdered iron material.
 18. A power supply, comprising: a printed circuit board; a two-phase coupled inductor affixed to the printed circuit board, the two-phase coupled inductor including: a magnetic core including a first side opposite a second side, the magnetic core forming a passageway extending through the core from the first side to the second side, the passageway partially defined by a first leg of the magnetic core, a first winding wound at least partially around the first leg and through the passageway, a first end of the first winding extending from the first side of the core and forming a first solder tab, a second end of the first winding extending from the second side of the core and forming a second solder tab, and a second winding wound at least partially around the first leg and through the passageway, a first end of the second winding extending from the first side of the core and forming a third solder tab, a second end of the second winding extending from the second side of the core and forming a fourth solder tab, wherein the first winding crosses the second winding within the passageway; a first switching circuit affixed to the printed circuit board and electrically coupled to the first solder tab, the first switching circuit configured to switch the first solder tab between at least two different voltage levels; a second switching circuit affixed to the printed circuit board and electrically coupled to the third solder tab, the second switching circuit configured to switch the third solder tab between at least two different voltage levels; and a conductive trace affixed to the printed circuit and electrically coupling together the second and fourth solder tabs.
 19. The power supply of claim 18 each of the first and second switching circuits being disposed along the first side of the magnetic core.
 20. The power supply of claim 19, each of the first and second switching circuits configured to switch at a frequency of at least 20 kilohertz, and the magnetic core being formed of a material selected from the group consisting of a ferrite material and a powdered iron material.
 21. A power supply, comprising: a printed circuit board; a two-phase coupled inductor affixed to the printed circuit board, the two-phase coupled inductor comprising: a magnetic core including a first side opposite a second side, a third side opposite a fourth side, and a fifth side opposite a sixth side, the fifth side connecting first side to the third side and forming an obtuse angle with the first side and an obtuse angle with the third side, the sixth side connecting the second side to the fourth side and forming an obtuse angle with the second side and an obtuse angle with the fourth side, the magnetic core forming a passageway extending through the core from the fifth side to the sixth side, the passageway partially defined by a first leg of the magnetic core, a first winding wound at least partially around the first leg and through the passageway, a first end of the first winding extending from the fifth side of the core and forming a first solder tab, a second end of the first winding extending from the sixth side of the core and forming a second solder tab, and a second winding wound at least partially around the first leg and through the passageway, a first end of the second winding extending from the fifth side of the core and forming a third solder tab, a second end of the second winding extending from the sixth side of the core and forming a fourth solder tab; a first switching circuit affixed to the printed circuit board and electrically coupled to the second solder tab, the first switching circuit configured to switch the second solder tab between at least two different voltage levels; a second switching circuit affixed to the printed circuit board and electrically coupled to the third solder tab, the second switching circuit configured to switch the third solder tab between at least two different voltage levels; and a conductive trace affixed to the printed circuit and electrically coupling together the first and fourth solder tabs.
 22. The power supply of claim 21, the first switching circuit being disposed along the first side of the magnetic core, and the second switching circuit being disposed along the fifth side of the magnetic core.
 23. The power supply of claim 22, each of the first and second switching circuits configured to switch at a frequency of at least 20 kilohertz, and the magnetic core being formed of a material selected from the group consisting of a ferrite material and a powdered iron material.
 24. A power supply, comprising: a printed circuit board; a two-phase coupled inductor affixed to the printed circuit board, the two-phase coupled inductor comprising: a magnetic core having a first side opposite a second side, the magnetic core forming a passageway extending through the core from the first side to the second side, the passageway partially defined by first and second opposing surfaces, the magnetic core including a first leg connecting the first and second surfaces within the passageway; a first winding wound at least partially around the first leg, a first end of the first winding extending from the first side of the core and forming a first solder tab, a second end of the first winding extending from the first side of the core and forming a second solder tab, and a second winding wound at least partially around the first leg, a first end of the second winding extending from the second side of the core and forming a third solder tab, a second end of the second winding extending from the second side of the core and forming a fourth solder tab; a first switching circuit affixed to the printed circuit board and electrically coupled to the first solder tab, the first switching circuit configured to switch the first solder tab between at least two different voltage levels; a second switching circuit affixed to the printed circuit board and electrically coupled to the third solder tab, the second switching circuit configured to switch the third solder tab between at least two different voltage levels; and a conductive trace affixed to the printed circuit and electrically coupling together the second and fourth solder tabs.
 25. The power supply of claim 24, each of the first and second switching circuits being disposed along a third side of the magnetic core.
 26. The power supply of claim 25, each of the first and second switching circuits configured to switch at a frequency of at least 20 kilohertz, and the magnetic core being formed of a material selected from the group consisting of a ferrite material and a powdered iron material. 